Indicating instrument switch



I INDICATING INSTRUMENT SWITCH Filed March 4 4 lllllllugmu human 2Sheets l ORNE S Oct. 21, 1930. HQSCHLAICH INDICATING INSTRUMENT SWITCHFiled March 4, 1924 2 Sheets-Sheet 2 a l E INVENTOR ATTORNEYS PatentedOct. 21, 193W want PATENT OFFEQE" HERMAN SGHLAICH, Q35 LONG ISLAND (KEY,NEW YORK HZDIGATING INSTRUMENT SWITCH Application filed March t,

This invention relates to announcing or' recording instruments, such asthermometers of the type adapted to announce or record when thetemperature has reached a predetermined point by giving an audible orvisible signal such as, for instance, ringing a bell or lighting alight.

t is an object of this invention to improve and simplify theconstruction of instruments m of this kind so as to reduce the costthereof and to render them less likely to get out of order and easier torepair than the prior instruments of this type.

Another object of the invention is to provide an announcing instrumentin which the expensive and delicate wiping electrical contactsheretofore used are replaced by simple, rugged and positively engagingcontacts, without subjecting the instrument to distorting strains whenthe movable element of the instrument is held stationary by theengagement of the rigid contact members.

Referring now to the drawings, which illustrate the invention embodiedin a thermometer: Figure 1 is a front elevation of such a thermometer;Figure 2 is a similar view with parts of the cover broken away to showthe interior construction of the de vice; Figure 3 is a longitudinalsectional 3O elevation through the thermometer casing; Figure 4 is adetail View of the Bourdon coil showing the compensating spring insidethe same; and Figure 5 is a rear view of the cover plate illustratingthe method of completing the electric circuit through the instrument.

The temperature indicating parts of the thermometer shown herein aredescribed and claimed in my copending application, Serial No. 696,562,filed March 3, 1924, to which reference may be had for a more completedescription of the same. The present application is a continuation inpart of this copending application, in which there is disclosed a bulbconnected by means of a flex 5 ible tubing, a Bourdon coil which,through nalling circuit is completed, are of the same 1924. Serial No.696,814.

a compensating coil, turns a hub to move a pointer over a scale.

They comprise briefly a bulb 1 connected by means of a flexible tube 2to a Bourdon coil 3. The bulb, tube and coil are filled with a suitabletemperature responsive fluid which, upon contract-ion or expansion,causes the coil 3 to coil or uncoil and, through the agency of acompensating coiled spring 3, to move the pointer 4 on the hub 4* backand forth over the, scale 5.

The hub 4* turns on a spindle 7- projecting out from the arbor 7 and theouter end of the Bourdon coil 3 is secured to a post 6 carried by arotatable plate 6 which is secured to the arbor 7, the center of thecoils 3 and 3 and the hub at being coincident with the spindle 7. Thearbor 7 is provided with a flange 7 adapted to bear on washersinterposed between it and the back of the indicator casing 9; and aplate 7, cooperating with said flange and secured to the casing 9 byscrews 7 serves to hold the flange 7" of the arbor 7 in frictionalengagement with said washers. The head of the arbor 7 projects into ahole 8 through the back of the indicator casing 9, and a screw driverslot 10 in the head of the arbor 7 provides a means for turning thearbor 7, the plate 6, the coils 3 and 3*, the hub 4* and the pointer 4carried thereby. for the purpose of adjusting the position of thepointer on the scale, as described in my copending application aboveidentified. A cover plate 11 is placed over the hole 8 to preventunauthorized tampering with the thermometer mechanism.

The hand or pointer 4 which is moved back and forth over the scale 5,and the set contact hand 12 through which the electric sigd shape andconstruction, so that hands formed by the same stamping operation may beused either as pointers 4 or as set contact hands 12. Each includes nearthe mid-portion thereof an enlargement 13 which is formed during theprocess of manufacture with three aligned holes 14.

In the middle hole 14, preferably on the indicating hand or pointer 4, acontact pin 15 is soldered or otherwise secured; and in the two outsideholes 14 in the set contact hand 12, a bridge or contact member 15 ismounted so as to project into the path of the pin 15 when the pointer 4moves over the scale to the position at which the set contact hand 12 isset.

The set contact hand 12 is mounted on a rotatable shaft 16 which passesthrough a disc of insulating material 17 held in the cover 18 of thecasing 9 by means of the screws 19.

On the outside of the casing, the shaft 16 is provided with a knurledknob 20 by which the shaft can be turned to set the contact hand 12 atthe desired point on the scale where the signal is to be given. To holdthe set contact hand 12 in the position to which it is turned, the shaft16 on the inside of the casing is bored to receive the pin 21 Y whichcooperates. with a bow shaped leaf spring 22 which is mounted betweenthe pin 21 and the back of the disc 17 and pulls the knob 20 into firmfrictional engagement with the face of the disc 17. Thus thecontactmember or contact hand 12 is rigidly adjustable.

When using the thermometer to announce any desired temperature by meansof audible or visible signals, one terminal of a battery 25 is connectedto the binding post 26 on the insulating block 17, and the otherterminal of the battery is connected through a bell or bulb 27 to thebinding post 28, which is elec-.

trically connected with the casing of the thermometer by the connector29. A connector 30 extends between the binding posts 26 and the shaft16.

Assuming that it is desired to have the thermometer announce thetemperature of 140 F., the hand 12 will be turned to 140, and when thehand 4 is turned to this point by the uncoiling of the Bourdon coil 3due to the expansion of the fluid in the bulb 1 by heat to which saidbulb may be subjected, the contacts 15 and 15 will meet, and the alarmcircuit will be completed from the battery 25 to the binding post 26,thence through the connector" 30 to the hand 12, thence through thecontacts 15* and 15 to the hand 4, thence through the indicatingmechanism and easing of the instrument and the connector 29 to thebinding post.28, and thence through the bell or bulb 27 back to thebat-' tery. After completion of this circuit, the bell or bulb 27 willcontinue to announce the temperature of 140, until the temperature isreduced and the hand 4 carrying the contact 15 moves away from. thecontact 15 and breaks the alarm circuit.

If, after the contact is made, the temperature should continue to riseand further uncoil the Bourdon coil 3, therebytending to move thepointer 4 higher'up the scale, the set contact hand 12 will prevent themovement of the hand 4, and the compensating coil 3 which is like a finehair spring of bimetallic material will then take up the strain on theinstrument parts, thereby preventing permanent distortion of either theBourdon coil or the pointer 4. When the temperature is lowered and thecontact 15 on the pointer 4 moves away from the contact 15 on the hand12, the compensating spring 3 will return to its normal position and thehub 4 and pointer 4 will return to their normal position, so that thethermometer will register temperatures as accurately as it did beforethe temperature responsive element was subjected to the distortingstrain.

' As described in my copending application above identified, the casing9of the present instrument is pivotally attached by means of the screws36 to a bracket support 31, so that, due to the flexibility of the tube2 and the braided cable 32 with which it is covered, the indicatingportion of the instrument may be tilted to various positions relative toits support and read with ease in any of its positions.

It will be seen that I have provided a very simple,-rugged andinexpensive announcing instrument which may-be safely subjected totemperatures in excess of that which it is set to announce, withoutdistorting or straining the same, and it is to be understood that thespecific embodiments of my invention which have been shown and describedherein are by way of example only, and that various modifications andchanges can be made therein without departing from the spirit of theinvention or the scope of the appended claims.

What I claim is: i

1. In an indicator of the type described. in combination, a scale, a setcontact hand, an indicating hand, means for moving the indieating-handback and forth over the scale,

including a Bourdon coil and a bimetallic compensating spring betweenthe Bourdon coil and the indicating hand, and rigid contact members onthe two hands, adapted to arrest the indicating hand and to makeelectrical contact with one another when the indicating hand reaches theposition at which the contact hand is set.

2. In an indicating and warning instrument of the type described, arigidly adjustable contact member, an indicating member movable into andout of contact with said contact member to close and open a signalclrcuit, and means for moving the indicating member, including a Bourdoncoil and a compensating coiled spring between the Bourdon coil and theindicating member.

3. In a temperature indicating and warnlng mstrument, in combination, atemperature responsive element, an indicator hand movable to indicatetemperatures at said ele ment, operating connectlons between the elementand the indicator hand comprising a Bourdon coil and a yieldingbi-metallic compensating spring, and a positive stop in the path of saidindicator hand for arresting it' and making contact with it when apre-determined temperature is reached to close a warning signal circuit.

In testimony whereof I have aflixed my signature to this specification.

HERMAN SCHLAICH.

